Comment on "Dislocation Structure and Mobility in hcp $^4$He"

TL;DR

This paper critiques a recent study on dislocation behavior in hcp helium-4, clarifying misconceptions about dislocation roles in giant plasticity and mass flow experiments.

Contribution

It provides a critical analysis of previous ab initio simulation results, clarifying the role of dislocations in helium-4's plasticity and mass flow phenomena.

Findings

Dislocations are not the primary cause of giant plasticity.

The interpretation of mass flow junction experiments is misleading.

Clarification of dislocation roles in helium-4.

Abstract

In their Letter, Borda, Cai, and de Koning report the results of ab initio simulations of dislocations responsible for the giant plasticity. The authors claim key insights into the recent interpretations of (i) the giant plasticity and (ii) the mass flow junction experiments. The purpose of this Comment is clarifying the role of dislocations in the mass flow in conjunction with explaining that the part (ii) of the claim is misleading.